氧化钙(100)、(110)和Ca-terminated(111)表面性能的第一性原理研究  

First-principles Study on CaO(100),(110)and Ca-terminated(111)Surface Properties

作　　者：韦柳婷[1] 童张法[1,2] 吴东海[1] 周思晨 王海晨[1] 罗涛朋 唐壁玉[1] 

机构地区：[1]广西大学化学化工学院,广西南宁530004 [2]广西碳酸钙产业化工程院,广西南宁530004

出　　处：《广西科学》2015年第6期670-674,680,共6页Guangxi Sciences

基　　金：广西科技攻关项目(桂科攻14122007-28)资助

摘　　要：【目的】对氧化钙(100)、(110)和Ca-terminated(111)的表面能、表面弛豫及电子结构进行系统研究。【方法】运用基于密度泛函理论的第一性原理计算体系的表面性能,计算过程采用6层原子和15真空层的Slab模型。【结果】计算得到的氧化钙体相晶格常数合理地符合实验值。氧化钙(100)面的表面能最低因而最稳定,更容易暴露。(110)面表面能介于(100)和Ca-terminated(111)面之间,Ca-terminated(111)面的表面能最高而最不稳定。(100)表面弛豫程度最弱,Ca-terminated(111)表面弛豫程度最明显,而(110)表面弛豫程度则介于(100)和Ca-terminated(111)面之间。(100)表面Ca-O和Ca-Ca之间的电子云强烈重叠,共价成键特征突出,稳定性高。Ca-terminated(111)表面只存在Ca-Ca原子间电子云重叠,且杂化程度明显变弱,因此Ca-terminated(111)面的稳定性最低,(110)面的稳定性居于(100)面与Ca-terminated(111)面之间。【结论】氧化钙中(100)面的表面稳定性能最好,(110)面次之,Ca-terminated(111)面稳定性最差。【Objective】The surface energy,surface relaxation and electronic structure of(100),(110)and Ca-terminated(111)surfaces for CaO were systemically investigated.【Methods】The surface properties were calculated using first-principle based on density functional theory.Sixlayer slab model with 15 A vacuum was used in all the calculations.【Results】The calculated lattice constants of bulk CaO agree reasonably with experimental values.The surface energy of(100)surface is lowest,suggesting that(100)surface is the most stable and is easy to expose outside.The surface energy of(110)surface is lower than that of Ca-terminated(111)surface,whereas the Ca-terminated(111)surface is most unstable due to the highest surface energy.The relaxation of(100)surface is the smallest,suggesting the strongest stability.Relaxation degree of(110)surface is between(100)and Ca-terminated(111)surfaces.In(100)surface,the over-laps of Ca-O and Ca-Ca electron clouds are more obvious than those of(110)surface,while the Ca-Ca overlap in Ca-terminated(111)surface is relatively weaker,indicating that surface stability is gradually lowered from(100),(110)to Ca-terminated(111)surface.【Conclusion】The(100)surface for CaO exhibits the most favorable properties,followed by(110)surface,and Ca-terminated(111)surface is most unstable.

关 键 词：氧化钙 表面能 稳定性 电子结构 第一性原理 

分 类 号：TQ132.32[化学工程—无机化工]